1. Technical Field
The present invention relates generally to a controller for an engine starter which may be employed in automotive vehicles, and more particularly to such a controller designed to release engagement of a pinion of the starter with a ring gear of an engine after completion of cranking of the engine.
2. Background Art
In typical automotive vehicles, starting of an engine after being stopped is achieved by applying initial torque to an output shaft (i.e., a crankshaft) of the engine using a starter. Specifically, a starter controller energizes the starter to thrust a pinion in an axial direction thereof and bring it into engagement with a ring gear coupled mechanically to the crankshaft of the engine. The starter controller then energizes an electric motor installed in the starter to rotate the ring gear through the pinion to crank the engine. Upon completion of cranking of the engine, the starter controller deenergizes the starter to stop the rotation of the pinion. For example, Japanese Patent First Publication No. 2002-70699 discloses such a starter controller.
The starter, as taught in the above publication, is equipped with a first combination of a relay switch and a transistor for energizing or denergizing a solenoid to thrust the pinion and a second combination of a relay switch and a transistor for energizing or denergizing the electric motor. The starter controller controls times of the energization or deenergization in the first and second combinations to control the thrust of the pinion and the rotation of the motor separately. When the engine has been cranked by the motor and started, the starter controller stops energizing the motor and then disengages the starter from the engine.
In the case where the disengagement of the starter from the engine after completion of cranking of the engine is achieved by turning off the motor to stop the pinion and then release the engagement of the pinion with the ring gear, the pinion will be rotated by the ring gear without being driven by the motor until the pinion is disengaged from the ring gear actually after the motor is stopped. This leads to a greater concern about the mechanical wear of the pinion.